Explaining what a capacitor is, we must clearly understand the physical basis of the operation and design of this indispensable element of every more or less serious electronic device.
A capacitor is an element of an electrical circuit consisting of two conductive plates, each of which contains an electric charge of the opposite sign. The plates are separated by a dielectric, which helps them retain this charge.
There are several types of insulating materials used in capacitors, including ceramic, mica, tantalum, and polystyrene. Insulators such as air, paper and plastic are also widely used in the manufacture of capacitors. Each of these materials effectively prevents the capacitor plates from touching each other.
What is the capacitance of a capacitor?
The concept of "capacitor capacitance" characterizes its ability to accumulate an electric charge. The unit of capacitance is Farad.
If a capacitor retains a charge of 1 pendant with a potential difference between its plates of 1 Volt, then it has a capacity of one Farad. In reality, this unit is too large for most practical applications. Typical valuescapacitances when using capacitors fall into the ranges of mifarad (10-3 F), microfarad (10-6 F) and picofarad (10-12 F).
What are capacitors?
To understand what a capacitor is, it is necessary to consider the main types of this component, depending on the purpose, application conditions and type of dielectric.
Electrolytic capacitors are used in circuits where high capacitance is required. Most of these elements are polar. Common materials for them are tantalum or aluminum. Aluminum electrolytic capacitors are much cheaper and have a wider application. However, tantalum has significantly higher volumetric efficiency and superior electrical performance.
Tantalum capacitors have tantalum oxide as a dielectric. They are characterized by high reliability, good frequency characteristics, wide operating temperature range. They are widely used in electronic equipment where a high level of capacitance is required in a small package. Due to their advantages, they are produced in large volumes for the needs of the electronics industry.
The disadvantages of tantalum capacitors include sensitivity to current ripple and overvoltage, as well as the relative high cost of these products.
Power capacitors are typically used in high voltage systems. They are widely used to compensate for losses in power lines, as well as to improve the power factor inindustrial electrical installations. Manufactured from high quality metallized propylene film with a special impregnation with non-toxic insulating oil.
May have a self-healing function for internal damage, which gives them additional reliability and increases their service life.
Ceramic capacitors have ceramic as the dielectric material. They feature high operating voltage functionality, reliability, low losses and low cost.
The range of capacitances varies from a few picofarads to about 0.1 uF. They are currently one of the most widely used types of capacitors used in electronic equipment.
Silver mica capacitors have replaced the previously widespread mica elements. Features high stability, sealed housing and large capacity per unit volume.
Wide use of silver-mica capacitors is hampered by their relative high cost.
Paper and metal-paper capacitors have plates made of thin aluminum foil, and special paper impregnated with a solid (molten) or liquid dielectric is used as a dielectric. They are used in low-frequency circuits of radio devices at high currents. They are relatively cheap.
What is a capacitor for
There are a number ofexamples of the use of capacitors for a wide variety of purposes. In particular, they are widely used for storing analog signals and digital data. Variable capacitors are used in telecommunications to adjust the frequency and tune telecommunications equipment.
A typical example of their application is the use in power supplies. There, these elements perform the function of smoothing (filtering) the rectified voltage at the output of these devices. They can also be used in voltage multipliers to generate high voltages many times the input voltage. Capacitors are widely used in various types of voltage converters, uninterruptible power supplies for computer equipment, etc.
Explaining what a capacitor is, one cannot fail to say that this element can also serve as an excellent storage of electrons. However, in reality, this function has certain limitations due to the imperfection of the insulating characteristics of the used dielectric. Nevertheless, the capacitor has the ability to store electrical energy for quite a long time when disconnected from the charge circuit, so it can be used as a temporary power source.
Due to their unique physical properties, these elements have found such widespread use in the electronics and electrical industries that it is rare today that an electrical product does not include at least one such component for any purpose.
Summing up, we can state that the capacitor isan invaluable part of a huge variety of electronic and electrical devices, without which further progress in science and technology would be unthinkable.
That's what a capacitor is!
